Fixing issues as per suggestions from @kevcunnane

src/Microsoft.SqlTools.ServiceLayer/Workspace/WorkspaceService.cs

@@ -0,0 +1,266 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.EditorServices.Utility;
+using Microsoft.SqlTools.ServiceLayer.Hosting;
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol;
+using Microsoft.SqlTools.ServiceLayer.Workspace.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.Workspace
+{
+    /// <summary>
+    /// Class for handling requests/events that deal with the state of the workspace, including the
+    /// opening and closing of files, the changing of configuration, etc.
+    /// </summary>
+    /// <typeparam name="TConfig">
+    /// The type of the class used for serializing and deserializing the configuration. Must be the
+    /// actual type of the instance otherwise deserialization will be incomplete.
+    /// </typeparam>
+    public class WorkspaceService<TConfig> where TConfig : class, new()
+    {
+
+        #region Singleton Instance Implementation
+
+        private static readonly Lazy<WorkspaceService<TConfig>> instance = new Lazy<WorkspaceService<TConfig>>(() => new WorkspaceService<TConfig>());
+
+        public static WorkspaceService<TConfig> Instance
+        {
+            get { return instance.Value; }
+        }
+
+        /// <summary>
+        /// Default, parameterless constructor.
+        /// TODO: Figure out how to make this truely singleton even with dependency injection for tests
+        /// </summary>
+        public WorkspaceService()
+        {
+            ConfigChangeCallbacks = new List<ConfigChangeCallback>();
+            TextDocChangeCallbacks = new List<TextDocChangeCallback>();
+            TextDocOpenCallbacks = new List<TextDocOpenCallback>();
+        }
+
+        #endregion
+
+        #region Properties
+
+        public Workspace Workspace { get; private set; }
+
+        public TConfig CurrentSettings { get; private set; }
+
+        /// <summary>
+        /// Delegate for callbacks that occur when the configuration for the workspace changes
+        /// </summary>
+        /// <param name="newSettings">The settings that were just set</param>
+        /// <param name="oldSettings">The settings before they were changed</param>
+        /// <param name="eventContext">Context of the event that triggered the callback</param>
+        /// <returns></returns>
+        public delegate Task ConfigChangeCallback(TConfig newSettings, TConfig oldSettings, EventContext eventContext);
+
+        /// <summary>
+        /// Delegate for callbacks that occur when the current text document changes
+        /// </summary>
+        /// <param name="changedFiles">Array of files that changed</param>
+        /// <param name="eventContext">Context of the event raised for the changed files</param>
+        public delegate Task TextDocChangeCallback(ScriptFile[] changedFiles, EventContext eventContext);
+
+        /// <summary>
+        /// Delegate for callbacks that occur when a text document is opened
+        /// </summary>
+        /// <param name="openFile">File that was opened</param>
+        /// <param name="eventContext">Context of the event raised for the changed files</param>
+        public delegate Task TextDocOpenCallback(ScriptFile openFile, EventContext eventContext);
+        
+        /// <summary>
+        /// List of callbacks to call when the configuration of the workspace changes
+        /// </summary>
+        private List<ConfigChangeCallback> ConfigChangeCallbacks { get; set; }
+
+        /// <summary>
+        /// List of callbacks to call when the current text document changes
+        /// </summary>
+        private List<TextDocChangeCallback> TextDocChangeCallbacks { get; set; }
+
+        /// <summary>
+        /// List of callbacks to call when a text document is opened
+        /// </summary>
+        private List<TextDocOpenCallback> TextDocOpenCallbacks { get; set; }
+
+
+        #endregion
+
+        #region Public Methods
+
+        public void InitializeService(ServiceHost serviceHost)
+        {
+            // Create a workspace that will handle state for the session
+            Workspace = new Workspace();
+            CurrentSettings = new TConfig();
+
+            // Register the handlers for when changes to the workspae occur
+            serviceHost.SetEventHandler(DidChangeTextDocumentNotification.Type, HandleDidChangeTextDocumentNotification);
+            serviceHost.SetEventHandler(DidOpenTextDocumentNotification.Type, HandleDidOpenTextDocumentNotification);
+            serviceHost.SetEventHandler(DidCloseTextDocumentNotification.Type, HandleDidCloseTextDocumentNotification);
+            serviceHost.SetEventHandler(DidChangeConfigurationNotification<TConfig>.Type, HandleDidChangeConfigurationNotification);
+            
+            // Register an initialization handler that sets the workspace path
+            serviceHost.RegisterInitializeTask(async (parameters, contect) =>
+            {
+                Logger.Write(LogLevel.Verbose, "Initializing workspace service");
+
+                if (Workspace != null)
+                {
+                    Workspace.WorkspacePath = parameters.RootPath;
+                }
+                await Task.FromResult(0);
+            });
+
+            // Register a shutdown request that disposes the workspace
+            serviceHost.RegisterShutdownTask(async (parameters, context) =>
+            {
+                Logger.Write(LogLevel.Verbose, "Shutting down workspace service");
+
+                if (Workspace != null)
+                {
+                    Workspace.Dispose();
+                    Workspace = null;
+                }
+                await Task.FromResult(0);
+            });
+        }
+
+        /// <summary>
+        /// Adds a new task to be called when the configuration has been changed. Use this to
+        /// handle changing configuration and changing the current configuration.
+        /// </summary>
+        /// <param name="task">Task to handle the request</param>
+        public void RegisterConfigChangeCallback(ConfigChangeCallback task)
+        {
+            ConfigChangeCallbacks.Add(task);
+        }
+
+        /// <summary>
+        /// Adds a new task to be called when the text of a document changes.
+        /// </summary>
+        /// <param name="task">Delegate to call when the document changes</param>
+        public void RegisterTextDocChangeCallback(TextDocChangeCallback task)
+        {
+            TextDocChangeCallbacks.Add(task);
+        }
+
+        /// <summary>
+        /// Adds a new task to be called when a file is opened
+        /// </summary>
+        /// <param name="task">Delegate to call when a document is opened</param>
+        public void RegisterTextDocOpenCallback(TextDocOpenCallback task)
+        {
+            TextDocOpenCallbacks.Add(task);
+        }        
+
+        #endregion
+
+        #region Event Handlers
+
+        /// <summary>
+        /// Handles text document change events
+        /// </summary>
+        protected Task HandleDidChangeTextDocumentNotification(
+            DidChangeTextDocumentParams textChangeParams,
+            EventContext eventContext)
+        {
+            StringBuilder msg = new StringBuilder();
+            msg.Append("HandleDidChangeTextDocumentNotification");
+            List<ScriptFile> changedFiles = new List<ScriptFile>();
+
+            // A text change notification can batch multiple change requests
+            foreach (var textChange in textChangeParams.ContentChanges)
+            {
+                string fileUri = textChangeParams.Uri ?? textChangeParams.TextDocument.Uri; 
+                msg.AppendLine(String.Format("  File: {0}", fileUri));
+
+                ScriptFile changedFile = Workspace.GetFile(fileUri);
+
+                changedFile.ApplyChange(
+                    GetFileChangeDetails(
+                        textChange.Range.Value,
+                        textChange.Text));
+
+                changedFiles.Add(changedFile);
+            }
+
+            Logger.Write(LogLevel.Verbose, msg.ToString());
+
+            var handlers = TextDocChangeCallbacks.Select(t => t(changedFiles.ToArray(), eventContext));
+            return Task.WhenAll(handlers);
+        }
+
+        protected async Task HandleDidOpenTextDocumentNotification(
+            DidOpenTextDocumentNotification openParams,
+            EventContext eventContext)
+        {
+            Logger.Write(LogLevel.Verbose, "HandleDidOpenTextDocumentNotification");
+
+            // read the SQL file contents into the ScriptFile 
+            ScriptFile openedFile = Workspace.GetFileBuffer(openParams.Uri, openParams.Text); 
+
+             // Propagate the changes to the event handlers
+            var textDocOpenTasks = TextDocOpenCallbacks.Select(
+                t => t(openedFile, eventContext));
+
+            await Task.WhenAll(textDocOpenTasks);
+        }
+
+        protected Task HandleDidCloseTextDocumentNotification(
+           TextDocumentIdentifier closeParams,
+           EventContext eventContext)
+        {
+            Logger.Write(LogLevel.Verbose, "HandleDidCloseTextDocumentNotification");
+            return Task.FromResult(true);
+        }
+
+        /// <summary>
+        /// Handles the configuration change event
+        /// </summary>
+        protected async Task HandleDidChangeConfigurationNotification(
+            DidChangeConfigurationParams<TConfig> configChangeParams,
+            EventContext eventContext)
+        {
+            Logger.Write(LogLevel.Verbose, "HandleDidChangeConfigurationNotification");
+
+            // Propagate the changes to the event handlers
+            var configUpdateTasks = ConfigChangeCallbacks.Select(
+                t => t(configChangeParams.Settings, CurrentSettings, eventContext));
+            await Task.WhenAll(configUpdateTasks);
+        }
+
+        #endregion
+
+        #region Private Helpers
+
+        /// <summary>
+        /// Switch from 0-based offsets to 1 based offsets
+        /// </summary>
+        /// <param name="changeRange"></param>
+        /// <param name="insertString"></param>       
+        private static FileChange GetFileChangeDetails(Range changeRange, string insertString)
+        {
+            // The protocol's positions are zero-based so add 1 to all offsets
+            return new FileChange
+            {
+                InsertString = insertString,
+                Line = changeRange.Start.Line + 1,
+                Offset = changeRange.Start.Character + 1,
+                EndLine = changeRange.End.Line + 1,
+                EndOffset = changeRange.End.Character + 1
+            };
+        }
+
+        #endregion
+    }
+}